TUP Message Screening

TUP messages are screened using the Allowed ISUP Message Type screen. The TUP protocol is an obsolete predecessor to the ISUP protocol that remains in use in some areas. To screen for TUP messages, a screen set must be defined to screen for messages containing the service indicator value of 4. This is accomplished by defining an allowed SIO screen in the screen set containing the si=4 parameter.

Since both ISUP and TUP messages are screened using the allowed ISUP message type screen, it is recommended that the screen set contain an allowed SIO screen to screen for ISUP messages, messages containing the service indicator value of 5. Each of these entries in the allowed SIO screen should have separate next screening functions. This allows the screening rules after the allowed SIO screen to have two separate streams, one that ends with screening ISUP messages, the other that ends with screening TUP messages.

The TUP messages can be screened for point codes before the allowed SIO screen with the allowed and blocked OPC screens, and after the SIO screen with the allowed and blocked DPC screens. However, if the screen set does not contain an allowed SIO screen that screens for TUP messages (messages with the service indicator value of 4), the message will be treated by the allowed ISUP message type screen as an ISUP message.

The following commands show how a screen set can be provisioned to screen for TUP and ISUP messages.

ent-scr-isup:sr=is01:isupmt=10:nsfi=stop

ent-scr-isup:sr=tu01:tupmt=1:nsfi=stop

ent-scr-dpc:sr=dpc4:ni=1:nc=2:ncm=3:nsfi=isup:nsr=tu01

ent-scr-dpc:sr=dpc5:ni=7:nc=1:ncm=0:nsfi=isup:nsr=is01

ent-scr-sio:sr=si02:nic=2:pri=0:si=4:nsfi=dpc:nsr=dpc4

ent-scr-sio:sr=si02:nic=2:pri=0:si=5:nsfi=dpc:nsr=dpc5

ent-scrset:scrn=ist2:nsr=si02:nsfi=sio

In this example screen set configuration, messages are screened by the allowed SIO screen si02 for either ISUP or TUP messages. ISUP messages are further screened by the allowed DPC screen dpc5 and TUP messages are screened by the allowed DPC screen dpc4. The ISUP messages containing the ANSI point code 001-002-003 are passed onto the allowed ISUP screen is01. The TUP messages containing the ANSI point code 007-001-000 are passed onto the allowed ISUP screen tu01.

Note:

The gateway screening rules are entered in reverse of the order that the screening process takes place.